Generation of spatially incoherent short pulses in laser-pumped neodymium stoichiometric crystals and powders

Gouédard, C.; Husson, D.; Sauteret, C.; Auzel, F.; Migus, A.

doi:10.1364/josab.10.002358

Cited by 279 publications

(124 citation statements)

References 18 publications

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“…Coherence is a fundamental characteristic of any laser, and, as such, the temporal coherence [3,4] and second-order coherence [5][6][7] of random lasers have been thoroughly investigated. However, the spatial coherence of random laser emission is not well understood despite initial observations indicating that it is much lower than in a conventional laser [4,[8][9][10]. Not only is spatial coherence of fundamental interest, but since this characteristic is likely to be quite different for random lasers than for conventional lasers, it could lead to a host of applications in which random lasers could outperform conventional lasers.…”

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confidence: 99%

Spatial coherence of random laser emission

2011

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Received Month X, XXXX; revised Month X, XXXX; accepted Month X, XXXX; posted Month X, XXXX (Doc. ID XXXXX); published Month X, XXXX We experimentally studied the spatial coherence of random laser emission from dye solutions containing nanoparticles. The spatial coherence, measured in a double-slit experiment, varied significantly with the density of scatterers and the size and shape of the excitation volume. A qualitative explanation is provided, illustrating the dramatic difference from the spatial coherence of a conventional laser. This work demonstrates that random lasers can be controlled to provide intense, spatially incoherent emission for applications in which spatial cross talk or speckle limit performance. © 2011 Optical Society of America OCIS Codes: 140.2050, 290.4210 Over the past two decades, random lasers have been the subject of intense theoretical and experimental studies [1,2]. Coherence is a fundamental characteristic of any laser, and, as such, the temporal coherence [3,4] and second-order coherence [5][6][7] of random lasers have been thoroughly investigated. However, the spatial coherence of random laser emission is not well understood despite initial observations indicating that it is much lower than in a conventional laser [4,[8][9][10]. Not only is spatial coherence of fundamental interest, but since this characteristic is likely to be quite different for random lasers than for conventional lasers, it could lead to a host of applications in which random lasers could outperform conventional lasers. For example, optical coherence tomography [11] and laser ranging [12] are limited by spatial cross talk and speckle and could benefit from the development of an intense, spatially incoherent light source.To this end, we present a systematic, experimental investigation of the spatial coherence of random laser emission. Specifically, we consider the effect on spatial coherence of the scatterer concentration, excitation volume, and pump intensity. Based on this work, we are able to identify regimes of operation in which a random laser provides spatially incoherent emission which could be used as a speckle-free laser probe beam.Our experiments were performed on a series of samples consisting of a laser dye solution and polystyrene spheres. The solution consisted of 5 mMol of Rhodamine 640 dissolved in diethylene glycol (DEG). The polystyrene spheres were each ~240 nm in diameter and their scattering cross section in DEG, σ, was calculated to be 1.67×10 -11 cm 2 . We fabricated samples with polystyrene sphere concentrations, ρ, of 1.2×10 12 cm -3 , 6.1×10 12 cm -3 , and 1.2×10 13 cm -3 . Since the average distance of adjacent scatterers was much larger than the diameter of the scattering cross section, light scattering by individual spheres was independent, and the scattering mean free path was estimated by ls=(ρσ) -1 to be 500 μm, 100 μm, and 50 μm, respectively.Lasing was achieved by optically exciting the dye solutions with a frequency-doubled Nd:YAG laser (wavelength λ = 532 nm) with 30 ps p...

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confidence: 99%

Spatial coherence of random laser emission

2011

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“…Both practical implementation and identification of this lasing mechanism are difficult and, because of this, no clear evidence for the optical feedback based on the scattering-mediated strong localization of light has so far been presented, except for maybe Ref. [88].…”

Section: Discussionmentioning

confidence: 99%

“…The threshold character of the optically pumped emitted intensity, together with the spectral and temporal narrowing of the emission line have been reported for different scattering media such as crystal powders [2,3,88,89], dispersions of solid-particle dye solutions [76,[90][91][92][93], organic films and opal crystals [77].…”

Section: Such a Phenomenon Of Trapping Of Electrons In Disordered Matmentioning

confidence: 95%

“…Unusual observations of the light emission lines akin to the resonant modes of the conventional lasers have been reported in Refs. [2,3,77,87,88] for the powder microcrystals. The threshold character of the emission intensity enhancement and the spectral and temporal narrowing of the emission lines are their common features.…”

Section: Such a Phenomenon Of Trapping Of Electrons In Disordered Matmentioning

confidence: 99%

“…Ref. [88] has been claimed to be a first observation of lasing in the regime of strong Anderson localization of light. The mean size of microcrystals has been of the order of several tens of nanometres, i.e.…”

Section: Such a Phenomenon Of Trapping Of Electrons In Disordered Matmentioning

confidence: 99%

See 2 more Smart Citations

Optically pumped mirrorless lasing. A review. Part I. Random lasing

Nastishin¹,

Dudok²

2013

Ukr. J. Phys. Opt.

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Abstract. Currently optically pumped mirrorless lasing is represented by three distinct branches, which concern lasing in different types of the gain media: optically random and photonic media, and microcavities. This article is a first part of our review on optically pumped mirrorless lasing, with the random lasing in scattering media being a main subject. The other mirrorless lasing mechanisms will be addressed in the second part. Considering light localization as a key function of the feedback, we discuss possible mechanisms for the light localization in the scattering media. Special attention is paid to the Anderson light localization. The other mechanisms of the light localization in the scattering media concern high Q-resonances in local microresonators, which exist due to structural inhomogeneities in the scattered media. Applications of the random lasers are shortly reviewed.

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Random Lasing in π-Conjugated Films and Infiltrated Opals

2001

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The properties of random lasers in π‐conjugated polymer films and solutions infiltrated into opal photonic crystals are reviewed. We show that random lasing is a generic phenomenon that occurs in disordered gain media at an excitation intensity regime higher than that giving rise to amplified spontaneous emission. The emission radiation is coherent as demonstrated by photon statistics methods, and its spectrum contains many laser modes from which a typical cavity length can be obtained using Fourier transform spectroscopy. Since the random cavities are independent from each other, we show that laser emission in several colors is possible when mixing different dyes in the same random cavities. In addition, it is demonstrated that random lasing is formed in many disordered media with various scattering properties ranging from a regime of light prelocalization to that of weak scattering.

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Generation of spatially incoherent short pulses in laser-pumped neodymium stoichiometric crystals and powders

Cited by 279 publications

References 18 publications

Spatial coherence of random laser emission

Spatial coherence of random laser emission

Optically pumped mirrorless lasing. A review. Part I. Random lasing

Random Lasing in π-Conjugated Films and Infiltrated Opals

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